Produce in high tunnels

Growing produce and cut flowers year-round could offer a potentially significant economic opportunity, and Mississippi State University researchers are collecting data to determine if it is a feasible strategy for the state’s growers.

Bill Evans is the leader of a team that received a nearly $500,000 competitive grant for a three-year project at two MSU and two growers’ sites. The project was supported by the National Research Initiative of the U.S. Department of Agriculture’s Cooperative State Research, Education and Extension Service.

“We are working with high tunnels, which are unheated greenhouses that allow us to extend the growing season later into the fall and earlier into the spring,” said Evans, the grant’s primary investigator. “We’re trying to see if we can start crops in the fall and grow them through the winter without heat using multiple covers inside these tunnels.”

Evans and his team will be growing tomatoes and zinnias in high tunnels at the Mississippi Agricultural and Forestry Experiment Station’s Truck Crops Branch in Crystal Springs, South Farm in Starkville, the Mayhew Tomato Farm in Lowndes County and Farm Fresh Produce in Stewart.

High tunnels, also known as hoop houses, work by using layers of plastic to trap warmer daytime air inside and minimize heat loss from the system at night. The layers of plastic insulate the plants from the cold temperatures outside the tunnel in much the same way that a person wears multiple layers of clothes to keep warm.

“Our model crops will be tomatoes and zinnias,” Evans said. “If we can grow and produce a tomato in the winter in Mississippi without heat, then we can produce just about anything. These are also high-dollar crops with good market potential.”

The grant will fund several research, graduate and laborer positions in MSU’s departments of plant and soil sciences and agricultural economics, and at the Truck Crops Branch Experiment Station in Crystal Springs.

“We made it a win-win-win situation,” Evans said. “The university, the Division of Agriculture, Forestry and Veterinary Medicine, and the scientists will win, and with the data, hopefully the growers and the state of Mississippi will win by having a greater availability of fresh produce and a more vibrant vegetable and cut flower industry.”

The high tunnel greenhouses being used are 12 feet high at the peak by 30 feet wide and 96 feet long. They contain about 2,800 square feet each and can be built for between $1 and $4 per square foot for a total cost of about $4,400 each. While similar to a traditional greenhouse, these are not permanent structures, and each has an expected use of five to 10 years.

The tunnel installation at the Truck Crops Experiment Station took less than two days and about 40 man-hours. Evans said they can be made from kits or off-the-shelf materials, allowing even the smallest grower to access the technology.

“All four sides can be raised to allow air inside to move freely,” Evans said. “The sides can open 4 feet high, while the ends can be completely opened to allow a tractor to plow through the tunnel.”

Plants are grown in the ground, and irrigation is necessary because the structure prevents rains from reaching the plants. Because the tunnels do not need electricity, they can be placed almost anywhere there is access to irrigation. Researchers don’t plan to screen the greenhouses to keep out pests.

“How a high tunnel climate interacts with insects and diseases in unknown in the South,” Evans said. “That’s one of the big questions we have as researchers, and although it is not our primary focus, information we gather will be useful in answering this question.”

In addition to Evans, researchers and Extension specialists on this project are horticulturists Mengmeng Gu and Guihong Bi, and agricultural economists Ken Hood and Randy Little.

Gu has the first Extension publication related to the project under review and is working on a Web site. These will provide a central location for information on high tunnel production. She will be involved in the project as the liaison between researchers and growers and in charge of outreach activities.

“There’s great interest among Mississippi producers in high tunnel production,” Gu said. “I’m just back from a North Carolina tour sponsored by the Mississippi Fruit and Vegetable Growers Association where high tunnel production was featured.

“There were about 30 producers from all around Mississippi on the trip. Some are a little suspicious about the technology and want to find out more, but I think most of them are very interested,” she said.

Gu said high tunnel production is feasible in the state.

“With high tunnels, we could grow a lot of crops with a longer growing season,” Gu said. “The fluctuation of temperatures, especially in early spring, makes it difficult to grow crops, but high tunnels help to minimize the fluctuation and increase nighttime temperature.”

The research tunnels will be available for tours from those interested in this technology. Contact Evans at (601) 892-3731 or Gu at (662) 325-1682.